Dimona, Israel — A Palestinian suicide bomber blew himself up at a shopping area Monday in this small town that is known to house Israel's secret nuclear program, killing one woman and injuring 11 other Israelis.

Israeli authorities said they were investigating exactly how the attackers – two men wearing explosive belts, one of whom was shot and killed before he could detonate his belt – had infiltrated Israel through Egypt. But a presuicide video by two young men in Gaza, filmed a week ago, made it clear by day's end that bombers had left Gaza during last month's break in the border wall with Egypt, gone to Gaza, and then had entered along the porous border with Israel.

Hard-liners in the coalition of Israeli Prime Minister Ehud Olmert claimed that the breach in the Gaza-Egypt border – created last month by Palestinian militants and sealed on Sunday – was to blame, and that negotiations with the Palestinians should stop.

"We need to return to the formula that we need to stop terror, and only after that we will speak, if there is [someone] with whom to speak," says Eli Yishai, the minister of industry, trade, and labor, while surveying the site of the attack. Mr. Yishai, also a deputy prime minister, is the head of Shas, an Orthodox Jewish party that has threatened to leave Mr. Olmert's coalition if the prime minister engages in discussions to divide Jerusalem into Israeli and Palestinian sections.

"We need to fix the border, and we need to return to control over the Philadelphia corridor," which divides Gaza from Egypt, Yishai adds. "We need to cope more seriously with the situation in Gaza; we've been too lax with what's happening there. There's no country in the world that would be quiet with these Qassam rockets being launched at us. We need to deal appropriately in the face of terror in Gaza and in the face of the border breakthrough."

Several different Palestinian groups claimed responsibility for the attack. But by afternoon it became certain that the bombers had been part of the Al-Aqsa Brigades, a militant offshoot of Fatah, the mainstream Palestine Liberation Organization (PLO) faction that is headed by Palestinian President Mahmoud Abbas. After the attack, Fatah flags hung outside the Gaza home of one of the bombers, 22-year-old Luay Laghwani, where relatives said he should be celebrated as a martyr, the Associated Press reported.

The suicide bombing, the first in a year, rattles the tentative return to Israeli-Palestinian peacemaking that was heralded in Annapolis, Md., last November, and which culminated in the visit to the region last month of President Bush, who has been pushing for a new Middle East peace deal by the end of his term.

Since Israel's well-guarded nuclear plant is more than six miles from the shopping center where the bombers struck, Israeli officials dismissed theories that this site was the true target. Dimona, mostly known as a hardscrabble desert town riddled with poverty, had never seen an incidence of terrorism. Most residents said that the quiet, off-the-radar feeling had abruptly come to an end.

Moshe Malka, a lawyer in the middle of a busy morning, heard the first explosion and ran downstairs. Amid the chaos and bloodshed, he saw an injured man lying on the ground and ran over to help him. Mr. Malka undid the man's jacket and saw that his middle was wrapped in an explosives belt.

In that moment, he said, he saw his life flash before his eyes.

"I yelled for everyone to go back. There was a wounded woman and so I picked her up to drag her away from the scene," he recalled, as he sits on a nearby park bench, shaking.

By then, police had already arrived. One of them, Koby Mor, said that as he got closer to the injured man wearing his explosives – apparently knocked down by his fellow bomber's explosion – Officer Mor shot in the direction of the man's head.

A rattled-looking man with bleary blue eyes said he had seen one of the bombers, sitting in a cafe and drinking a coffee, just before he got up, walked away, and pushed the button.

"He drank an espresso before he blew himself up," cried Arik Ben David, who said he was in the same cafe, and noticed a man in a wide coat, who then rose from his seat somewhat awkwardly.

"He paid 50 shekels [about $14 – too much for a coffee] and didn't wait for his change," Mr. Ben David continued. "I saw that he walked to a group of people and heard they were speaking Arabic, and he didn't blow himself up. He kept on going."

A few hours after the attack, Israeli aircraft struck a car in northern Gaza, killing a top military commander in the Popular Resistance Committee (PRC), a group made up of several Palestinian factions and which is active in launching Qassam rockets into Israel.

Elsewhere in Gaza, Palestinians celebrated the attack in Dimona and distributed candy.

After more than a week of Gazans entering Egypt more or less freely, Egyptian police resealed the border on Sunday. Israeli and Palestinian media sources reported that on Monday night, the border crossing between Egypt and the Gaza Strip was reopened following a day of clashes between Egyptian troops and Palestinians stuck on the Egyptian side of the border.

Palestinian President Abbas condemned the Dimona bombing.

Olmert, speaking at the Knesset, said that Israel was facing a war in its south and would not waver in fighting it. "This war will continue. Terrorism will be hit. We will not relent," he said.